There is a known conventional server system that allocates device unique information, such as a host ID or a media access control (MAC) address, to each physical partition in which a single Operating System (OS) is operated. Such a server system is shipped such that, in order to set device unique information in each physical partition, the number of pieces of device unique information and the maximum number of settings of the physical partitions are previously set to the same number.
In the following, an example of a server system that includes a casing in which device unique information is previously set will be described with reference to FIG. 12. FIG. 12 is a schematic diagram illustrating a conventional server system. In the example illustrated in FIG. 12, a server system 50 includes, in a casing 51, four system boards (SB) 52 to 55, a managing unit 56a, which is an active managing unit, a managing unit 56b, which is a standby managing unit, a FAN 57, and a power supply unit (PSU) 58.
Because the SBs 52 to 55 implement services provided by the server system 50, each of the SBs 52 to 55 is an information processing apparatus that executes various applications. For example, the SB 52 includes multiple central processing units (CPUs) #0 to #3, a system controller (SC), and a memory and it executes various applications that provide the services. The FAN 57 is a cooling fan that cools each of the SBs 52 to 55. The PSU 58 is an electrical power supply device that supplies electrical power to the SBs 52 to 55, to the managing unit 56a, to the managing unit 56b, and the like.
When the server system 50 operates each SB as a single physical partition, the casing 51 described above is shipped in a state in which four pieces of device unique information are previously set up in the managing unit 56a. Then, when the casing 51 is booted up, the managing unit 56a allocates, one by one, the device unique information to each of the SBs 52 to 55. Then, each of the SBs 52 to 55 provides a service by using the device unique information allocated by the managing unit 56a. 
Because the server system 50 operates as a system that continues its operation even if a failure occurs, the server system 50 includes, in addition to the active managing unit 56a, the standby managing unit 56b. If the managing unit 56a fails, the server system 50 allows the managing unit 56a to notify the managing unit 56b of various kinds of setting information on each of the SBs 52 to 55 including the device unique information and continues its operation by using the managing unit 56b. 
In contrast, in addition to the system in which multiple SBs are in a single casing, there is a known server system that uses a building block (BB) system that includes multiple casings that independently operate. The server system that uses such a building block system is constructed for each casing regardless of the size of the system. In the following, a server system that uses the building block system will be described with reference to FIG. 13.
FIG. 13 is a schematic diagram illustrating an example of a server system that uses a building block system. As illustrated in FIG. 13, a server system 60 that uses the building block system includes multiple casings 61 to 64 and each of the casings 61 to 64 is connected by a network. Furthermore, the casing 61 includes CPUs #0 to #3, an SC, a memory, a managing unit 56c, the FAN 57, and the PSU 58. Furthermore, it is assumed that the casings 62 to 64 are the same as the casing 61.
If the device unique information allocated to each physical partition is changed, a setting change task for each application is needed. To avoid a change in device unique information due to an increase or a decrease in the number of physical partitions, each of the casings 61 to 64 are shipped in a state in which the maximum number of device unique information used by the server system 60 is previously set up in the managing unit in each of the casings 61 to 64.
Then, by using the device unique information previously set up in the managing unit in the casing operating as an active casing, the server system 60 executes an OS or the like and provides a service. For example, if the server system 60 uses the casing 61 as an active casing, the managing unit 56c in the casing 61 notifies the OS of the previously set device unique information and provides the service.
Patent Document 1: Japanese Laid-open Patent Publication No. 2010-233006
Patent Document 2: Japanese Laid-open Patent Publication No. 2010-147929
However, with the server system in the building block system described above, because the maximum number of pieces of device unique information used by the server system is previously set up in the managing unit in each of the casings, there is a problem in that device unique information that is not used is still present.
For example, if the maximum number of pieces of device unique information used by the server system 60 is four, each of the casings 61 to 64 is shipped in a state in which four pieces of device unique information are previously set up in the managing unit. Then, if the server system 60 uses the casing 61 as an active casing, the casing 61 executes an OS by using the device unique information that has been previously set up in the managing unit 56c. 
Then, the server system 60 operates while 12 pieces of unused device unique information are set up in the casings 62 to 64. At this point, device unique information, such as a host ID or a MAC address, is used to manage the licenses of software and acquiring MAC addresses and the like is an expense. Consequently, the server system 60 increases a cost for itself.